As part of the physiological process leading to ovulation, luteinizing hormone causes a rise in prostaglandin levels in preovulatory ovarian follicles. The objective of this proposal is the elucidation of the biochemical events by which luteinizing hormone stimulates this synthesis of prostaglandins in follicular granulosa cells of the rat ovary. Our previous studies have shown that luteinizing hormone produces an increase in the quantity of prostaglandin synthetase activity in granulosa cells. The proposed experiments are designed to test the possibility of enzyme(s) activation versus production of new enzyme(s), as well as to probe the events leading to either of these possibilities. The methodologies to be utilized include generation and testing of intermediates in the biochemical pathway, kinetic analysis of enzyme activity, immunochemical assessment of the amount of enzyme present and specific enzyme labeling with (3H-acetyl)aspirin. In addition, studies will be carried out to evaluate the roles of cyclic AMP, polyamines, and proteolysis in the prostaglandin response to luteinizing hormone. These investigations should identify the biochemical mechanism by which luteinizing hormone stimulates the synthesis of follicular prostaglandins. The prostaglandins and related substances have been ascribed important roles in many areas of mammalian physiology. The proposed research may, therefore, have implications beyond its immediate goal of understanding the hormonal control of prostaglandin synthesis in ovulation.